21663364 has 6 divisors (see below), whose sum is σ = 37910894. Its totient is φ = 10831680.

The previous prime is 21663359. The next prime is 21663373. The reversal of 21663364 is 46336612.

It can be written as a sum of positive squares in only one way, i.e., 11614464 + 10048900 = 3408^2 + 3170^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2707917 + ... + 2707924.

Almost surely, 2^21663364 is an apocalyptic number.

It is an amenable number.

21663364 is a deficient number, since it is larger than the sum of its proper divisors (16247530).

21663364 is a wasteful number, since it uses less digits than its factorization.

21663364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5415845 (or 5415843 counting only the distinct ones).

The product of its digits is 15552, while the sum is 31.

The square root of 21663364 is about 4654.3919044275. The cubic root of 21663364 is about 278.7673878970.

Adding to 21663364 its reverse (46336612), we get a palindrome (67999976).

The spelling of 21663364 in words is "twenty-one million, six hundred sixty-three thousand, three hundred sixty-four".